Resolve "Include Mann-Whitney U rank test"

See merge request !380

Merge branch 'lukas_issue353_feat_filter-dh-differentiate-extend_length_opts-and-offset' into 'develop'

Resolve "filter dh: differentiate between history offset and information offset"

See merge request !378

Merge branch 'lukas_issue358_bug_order-in-feature_importance_bootstrap_method-causes-crash' into 'develop'

Resolve "Bug: order in feature_importance_bootstrap_method causes crash"

See merge request !383

Merge branch 'lukas_issue358_bug_order-in-feature_importance_bootstrap_method-causes-crash' into felix_TF2_merge_test

Resolve "REFAC: remove hard coded type dim from skill score"

See merge request !382

Merge branch 'lukas_issue356_feat_can-define-names-of-branches-to-use-in-feature-importance' into 'develop'

Resolve "can define names of branches to use in feature importance"

See merge request !381

Merge branch 'felix_issue354-allow-fixed-variable-list-for-feature-importance-boots' into sectorial_bootstraps

use class variables for chem and meteo names, is now able to distinguish for all parameters of the data handler if provided as dict with respective keys, only use test stations for block mse calculation